Staying on the right side of legionella law

Recent changes to legionella regulations by the health and safety executive (HSE) have put greater responsibility on businesses to actively manage the legionella risk in their water systems. Businesses failing to meet the new regulations could face prosecution as part of a concerted effort to drive improvements in the sector. Here Dr. Simona Vasilescu, from the Water Treatment Innovation Platform at NCH Europe, looks at what businesses need to do to stay in control.

Ingested, the bacterium Legionella pneumophilia is relatively harmless. After all, it exists in low numbers in natural water sources such as rivers, lakes and reservoirs. However, trapped in a microscopic droplet of water vapour and breathed into your lungs, it can lead to the potentially fatal Legionnaires' disease. With symptoms resembling the common cold, this disease can be even more difficult to diagnose at first glance.

Although everyone is susceptible to the risk of infection, the likelihood is exacerbated with age and in people with weaker immune systems such as diabetics, smokers and heavy drinkers.

While the concentration of legionella bacteria is relatively low in nature, it can quickly multiply upon entering a business's water supply. The warm, humid conditions created by stagnant water in storage tanks, heat exchangers and miles of piping, provide a thriving breeding-ground that can quickly harbour a breakout.

Regulatory reform

To drive improvements in the health and safety of people at work, the UK Government is keen to crack down on premises at risk. The Health and Safety Executive (HSE) has issued new guidelines called the L8 Approved Code of Practice (ACoP), fourth edition. These guidelines are accompanied by technical guidance documents in three parts to make it easier for businesses to comply with the law.

The new rules now increase the responsibility on companies and on specific people of responsibility within them. 'Dutyholders' such as employers, landlords and those in-charge of any site, now have a legal responsibility to identify and manage the risk of exposure to legionella, develop preventative and control measures, ensure the process is recorded using a regularly updated, 'living document' and appoint a competent authority to implement the control measures.

Step by step

So what do you need to do to make sure your system is not at risk? The first stage is to establish whether your site is low risk or not. If you're in a small building with no water storage tanks, where the cold water comes directly from the mains and hot water is fed directly from instantaneous or low volume water heaters at around 50 degrees Celsius, then there is very little risk of exposure to individuals. Here, the only source of risk is from toilets and hand washbasins.

If you are low risk, you don't need to take further control action. You simply need to perform a regular risk assessment, document the process, and review it when changes are made to the system.

For businesses operating in anything other than a small building, for example if you're running a plant, the risk is much higher. Facilities that have more complex water systems need to create an asset register; a schematic diagram of the system highlighting deadlegs - lengths of pipework where water can stagnate - and identifying possible sources of contamination as well as assessing current disinfection and treatment methods.

A water system includes all the plant equipment and installed components such as pipes, pumps, feedtanks, showers, heat exchangers, quench tanks, water softeners, chillers and humidifiers to name just a few. These kinds of setups are very conducive to stagnant water temperatures between 20-45 degrees Celsius in water sources, which can lead to spray and legionella laden aerosols.

As a business, it's often easy to overlook the fact that although the mains utility has a responsibility to provide a bacteria-free water supply, once the mains supply enters the building at the ball valve, even small amounts of bacteria can quickly multiply. Pipes under buildings and facilities are often decades old, containing rust, slime and microbiological films. These are perfect environments for legionella to thrive.

Stress free

For many companies it can become a nightmare to take control of this process. Although temperature-based monitoring is straightforward, many businesses simply don't have the expertise to deal with the more complex control methods that include chemical dosing and water treatment. Luckily, the regulations make it permissible for businesses to appoint a competent authority to manage the assessment and control of legionella.

When it comes to water treatment, it's important to select the right chemicals. Whether it's chlorine, bromine or any oxidising biocide, understanding contact time, system water-turnover rates and half-life are essential in developing a sustainable long term treatment plan. It's also more cost effective to outsource the site-survey assessment and monitoring to an expert that really understands how to keep your business compliant.

The new rules are certainly clearer in defining the responsibility of businesses when it comes to mitigating the risks of legionella exposure. While at first this may seem daunting, with the right help and use of control methods, businesses can not only comply with the law but also become examples of best practice.